/**
 * Copyright 2012 Brigham Young University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package edu.byu.nlp.cluster.mom;

import edu.byu.nlp.util.Matrices;

/**
 * @author  rah67
 */
public class HyperParams {

	private final double alpha;
	private double beta;
	private final double[] alphaPlusObservedCounts;
	private final double[][] betaPlusObservedCounts;

	public HyperParams(double alpha, double beta, double[] alphaPlusObservedCounts, double[][] betaPlusObservedCounts) {
		this.alpha = alpha;
		this.beta = beta;
		this.alphaPlusObservedCounts = alphaPlusObservedCounts;
		this.betaPlusObservedCounts = betaPlusObservedCounts;
	}

	public double getAlpha() {
		return alpha;
	}

	public double getBeta() {
		return beta;
	}

	public void setBeta(double beta) {
		// Update prior counts
		Matrices.addToSelf(betaPlusObservedCounts, beta - this.beta);
		this.beta = beta;
	}

	public double[] getAlphaPlusObservedCounts() {
		return alphaPlusObservedCounts;
	}

	public double[][] getBetaPlusObservedCounts() {
		return betaPlusObservedCounts;
	}
	
	public static HyperParams fromCopy(double alpha, double beta, double[] alphaPlusObservedCounts,
			double[][] betaPlusObservedCounts) {
		return new HyperParams(alpha, beta, alphaPlusObservedCounts.clone(), Matrices.clone(betaPlusObservedCounts));
	}
}